Re: [PATCH v1 16/17] intel_iommu: Modify x-scalable-mode to be string option

[CLEMENT MATHIEU--DRIF]

On 19/07/2024 04:53, Duan, Zhenzhong wrote:
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>
>> -----Original Message-----
>> From: CLEMENT MATHIEU--DRIF <clement.mathieu--drif@eviden.com>
>> Subject: Re: [PATCH v1 16/17] intel_iommu: Modify x-scalable-mode to be
>> string option
>>
>>
>>
>> On 18/07/2024 10:16, Zhenzhong Duan wrote:
>>> Caution: External email. Do not open attachments or click links, unless this
>> email comes from a known sender and you know the content is safe.
>>>
>>> From: Yi Liu <yi.l.liu@intel.com>
>>>
>>> Intel VT-d 3.0 introduces scalable mode, and it has a bunch of capabilities
>>> related to scalable mode translation, thus there are multiple combinations.
>>> While this vIOMMU implementation wants to simplify it for user by
>> providing
>>> typical combinations. User could config it by "x-scalable-mode" option. The
>>> usage is as below:
>>>
>>> "-device intel-iommu,x-scalable-mode=["legacy"|"modern"|"off"]"
>>>
>>>    - "legacy": gives support for stage-2 page table
>>>    - "modern": gives support for stage-1 page table
>>>    - "off": no scalable mode support
>>>    -  if not configured, means no scalable mode support, if not proper
>>>       configured, will throw error
>> s/proper/properly
>> Maybe we could split and rephrase the last bullet point to make it clear
>> that "off" is equivalent to not using the option at all
> You mean split last bullet as a separate paragraph?
> Then what about below:
>
>    - "legacy": gives support for stage-2 page table
>    - "modern": gives support for stage-1 page table
>    - "off": no scalable mode support
>    -  any other string, will throw error
>
> If x-scalable-mode is not configured, it is equivalent to x-scalable-mode=off.
Yes, lgtm
>
> Thanks
> Zhenzhong
>
>>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>>> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
>>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>> ---
>>>    include/hw/i386/intel_iommu.h |  1 +
>>>    hw/i386/intel_iommu.c         | 24 +++++++++++++++++++++++-
>>>    2 files changed, 24 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/include/hw/i386/intel_iommu.h
>> b/include/hw/i386/intel_iommu.h
>>> index 48134bda11..650641544c 100644
>>> --- a/include/hw/i386/intel_iommu.h
>>> +++ b/include/hw/i386/intel_iommu.h
>>> @@ -263,6 +263,7 @@ struct IntelIOMMUState {
>>>
>>>        bool caching_mode;              /* RO - is cap CM enabled? */
>>>        bool scalable_mode;             /* RO - is Scalable Mode supported? 
>>> */
>>> +    char *scalable_mode_str;        /* RO - admin's Scalable Mode config */
>>>        bool scalable_modern;           /* RO - is modern SM supported? */
>>>        bool snoop_control;             /* RO - is SNP filed supported? */
>>>
>>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>>> index 2804c3628a..14d05fce1d 100644
>>> --- a/hw/i386/intel_iommu.c
>>> +++ b/hw/i386/intel_iommu.c
>>> @@ -3770,7 +3770,7 @@ static Property vtd_properties[] = {
>>>        DEFINE_PROP_UINT8("aw-bits", IntelIOMMUState, aw_bits,
>>>                          VTD_HOST_AW_AUTO),
>>>        DEFINE_PROP_BOOL("caching-mode", IntelIOMMUState, caching_mode,
>> FALSE),
>>> -    DEFINE_PROP_BOOL("x-scalable-mode", IntelIOMMUState,
>> scalable_mode, FALSE),
>>> +    DEFINE_PROP_STRING("x-scalable-mode", IntelIOMMUState,
>> scalable_mode_str),
>>>        DEFINE_PROP_BOOL("snoop-control", IntelIOMMUState,
>> snoop_control, false),
>>>        DEFINE_PROP_BOOL("x-pasid-mode", IntelIOMMUState, pasid, false),
>>>        DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true),
>>> @@ -4686,6 +4686,28 @@ static bool
>> vtd_decide_config(IntelIOMMUState *s, Error **errp)
>>>            }
>>>        }
>>>
>>> +    if (s->scalable_mode_str &&
>>> +        (strcmp(s->scalable_mode_str, "off") &&
>>> +         strcmp(s->scalable_mode_str, "modern") &&
>>> +         strcmp(s->scalable_mode_str, "legacy"))) {
>>> +        error_setg(errp, "Invalid x-scalable-mode config,"
>>> +                         "Please use \"modern\", \"legacy\" or \"off\"");
>>> +        return false;
>>> +    }
>>> +
>>> +    if (s->scalable_mode_str &&
>>> +        !strcmp(s->scalable_mode_str, "legacy")) {
>>> +        s->scalable_mode = true;
>>> +        s->scalable_modern = false;
>>> +    } else if (s->scalable_mode_str &&
>>> +        !strcmp(s->scalable_mode_str, "modern")) {
>>> +        s->scalable_mode = true;
>>> +        s->scalable_modern = true;
>>> +    } else {
>>> +        s->scalable_mode = false;
>>> +        s->scalable_modern = false;
>>> +    }
>>> +
>>>        if (s->aw_bits == VTD_HOST_AW_AUTO) {
>>>            if (s->scalable_modern) {
>>>                s->aw_bits = VTD_HOST_AW_48BIT;
>>> --
>>> 2.34.1
>>>
>> LGTM